Are there any new Code requirements for 600V or less motor control centers, that require engineeering practices to prevent or keep a technician from having to be exposed to energized starter/breaker when performing task such as troubleshooting or monitoring?

There are not any codes or standards that require this sort of isolation during troubleshooting, although some companies have internal standards moving in this direction. There is one relevant IEEE document that is currently in the draft stage - IEEE 1683 "Guide for Motor Control Centers Rated Up To and Including 600 Vac or 1000 Vdc with Requirements Intended to Reduce Electrical Hazards While Performing Defined Operations."

There are a number of suggestions in IEEE 1683 related to your question:
- Consider using a control voltage less than 50V to reduce the hazard to troubleshooting control circuits
- Consider use of test power so that the primary voltage can be isolated from the compartment while troubleshooting the control circuit.
- Consider use of insulated bus in all practical locations.
- Consider use of shutters wherever practical to isolate personnel and tools from live parts
- Consider use of "finger safe" components wherever possible
- Consider maximizing the use of "arc free zones", which are defined as areas where it is not possible to install a fuse wire to initiate an arc. A high percentage of arc flash incidents are initiated by humans, and by insulating or guarding live parts such that it's not possible to install a fuse wire we can decrease the probability of initiating an incident.

This is off the top of my head right now, I'm sure there are a number of things I'm forgetting. The goal is to finalize IEEE 1683 by the Electrical Safety Workshop in late January 2012 and publish the guide in 2012.